Automotive vehicles are commonly equipped with exterior side view mirrors positioned on opposite sides of the vehicle to allow the driver to see a portion of the roadway generally behind and to the sides of the host vehicle with only a slight shift of the eyes or turn of the driver's head. When changing lanes, the driver may view the side of the vehicle via the appropriate side view mirror to confirm that the adjacent lane of the roadway is clear to make a lane change. Unfortunately, many vehicles exhibit a space that is generally unviewable via the mirrors, commonly referred to as the “blind spot” or “blind zone.”
To help vehicle drivers negotiate the roadway, detection systems have been proposed to detect objects located within a vehicle blind spot region. Additionally, warning systems may be provided to alert vehicle operators of detected objects that may be a collision hazard when the object is in close proximity to the host vehicle. For example, when changing lanes, the vehicle warning system may warn of an object located in the lane adjacent to the vehicle, particularly in a blind zone which may not be easily viewable by the driver. The warning may allow sufficient reaction time for the vehicle operator to respond to prevent an undesirable collision.
Detection systems have been proposed that employ various sensing arrangements for detecting an object and alerting the driver of the host vehicle of the presence of an object in the blind spot region. Examples of proposed vehicle detection systems are disclosed in U.S. Pat. Nos. 6,961,006; 6,753,766 and 5,668,539, the entire disclosures of which are hereby incorporated herein by reference. The approaches disclosed in the aforementioned patents generally employ passive infrared sensors, such as thermopile sensors, to detect changes in the thermal scene along the side of a host vehicle to detect the presence of a thermal emitting object, such as another vehicle, in a blind spot region of the vehicle. Some of these proposed detection techniques generally employ a time shift in sensed thermal temperature measurements so as to generally match the sensing zones to the speed of the vehicle.
Additionally, the thermal radiation detectors employed by various proposed blind spot detection systems typically employ multiple thermal detection sensors having separate lens elements and duplicative components. Examples of thermal radiation detectors are disclosed in U.S. Pat. No. 7,148,482 and U.S. Patent Application Publication No. 2006/0067378, the entire disclosures of which are hereby incorporated herein by reference. Some infrared detection systems may not adequately detect smaller objects, such as compact vehicles and motorcycles, and may not timely detect movement of such vehicles into the host vehicle blind zone, particularly from a distance beyond the adjacent lane.
It is therefore desirable to provide for a blind spot detection system that detects objects, such as another vehicle, in a timely fashion. It is further desirable to provide for a thermal radiation detector that may be employed on a vehicle to adequately detect objects in various sizes, including compact vehicles.